This invention relates to a new and improved method of assembling molds and more particularly to a method of assembling molds by using a fixture to position mold sections relative to each other during the forming of a mold.
Circular turbine engine components have frequently been cast from one piece ceramic molds. The molds have been formed by using wax patterns which are covered with a wet coating of ceramic mold material. The wet covering of ceramic mold material is dried and fired at a relatively high temperature to eliminate the way pattern and fire the ceramic mold material to form a rigid mold. One known method of making turbine engine components in this manner is disclosed in U.S. Pat. No. 3,669,177.
When this known method of forming engine turbine components is utilized, the dimensions of the cast components may differ from the design or intended dimensions due to inaccuracies in the forming of the mold. Although there are many different factors which contribute to inaccuracies in the formation of the mold, shrinkage of the wax pattern, dimensional changes in the ceramic mold during drying and firing, and shrinkage of the casting material upon cooling all contribute to dimensional inaccuracies in the final cast product.
There are several known ways of compensating for the inaccuracies in the cast product. One of these is to form the cast product oversize and then machine it down to the desired dimensions. Another way of compensating for inaccuracies in the cast product is to change the metal dies used in forming the wax pattern. Both of these methods of compensating for dimensional inaccuracies in a cast product are expensive and time consuming.